CCNA Discovery 1, Chapter 3

3.4.1–3.4.3: Table 28-1 compares the functions of hubs and switches at a network’s access layer.

Table 28-1. Functions of Hubs and Switches

3.4.4: When a host application intends to send a frame to all other hosts on a network, it sends a broadcast message. Broadcast messages use FFFF.FFFF.FFFF as the destination MAC address. A switch broadcasts this message to all hosts, and all hosts process the message. A network connected with switches and hubs is a single broadcast domain.

3.4.6 and 3.4.7: When an application intends to send information to another host, but it knows only the IP address of the destination, the sending host can use address resolution protocol (ARP). ARP is an IP protocol that finds a destination MAC when only the destination IP is known. The sending host broadcasts a frame with the IP address. Each host on the network looks for a match with its IP, and the matching host responds with the proper MAC address. If the IP is from another network, the router typically responds with the router’s MAC address.